Between 1857 and 1877, a mysterious outlaw called "The Sidewinder" leads a group of renegade Utes in brutal attacks on Arizona settlers. When he destroys the Canyon Diablo ranch of Tex McCloud, the rancher determines to bring the killer to justice. One evening, while drinking at the Last Chance Saloon, Tex criticizes the Cavalry for letting The Sidewinder elude them for so many years. This provokes Lt. Tom Blaine into betting a year's salary that the Cavalry will beat Tex in finding the criminal. Carolina, an attractive saloon entertainer, offers to cover Tex's half of the bet, and later, promises him a profitable mining stake in exchange for helping her to collect a debt from Lucky Lee, a wealthy mine owner in Fort Savage, who owes her $20,000. Carolina plans to have the handsome Tex capture the heart of Lucky's sweetheart, Nora Logan, then upon receipt of her money, will guarantee Tex's departure from the scene. Tex rejects Carolina's offer and checks into a seedy hotel, where he encounters Nora. Distressed that her door lock is broken, Nora accepts Tex's offer to exchange rooms. That night, however, gambler Showdown Calhoun and his partner Lafe break into Nora's room. Realizing that Carolina is behind the attack, Tex angrily orders them away at gunpoint, thereby earning Nora's gratitude. The next morning, Nora and Carolina both board the Fort Savage stagecoach. Upon learning that Showdown and his cohort left town earlier in the day, Tex leaps onto his horse and catches up with the stage just after the two men kidnap Nora. Tex rescues her and then accompanies the stage to Fort Savage. Nora introduces Tex to Lucky, who offers to repay the rancher for protecting his bride-to-be. Tex asks for a new rifle and returns to his room, where Carolina once again suggests that the two of them team up to collect the $20,000. Tex angrily rejects Carolina's advances and throws her out. The next day, Tex visits Lucky's trading post, where he learns that Nora, who had been kidnapped by The Sidewinder's men several years earlier, is marrying Lucky out of gratitude for his subsequent purchase of her freedom. While browsing in the trading post, Tex sees his own rifle for sale, and Lucky explains that his man, Hopi Joe, had earlier bought the Winchester from an outlaw named Tombstone Jack. Lucky suggests that Tombstone must be The Sidewinder, but later, he warns Tombstone that Tex is planning to kill him. When Tombstone attacks Tex that night, Tex injures him and accuses him of being The Sidewinder. Tombstone's friend Jeb Weaver, however, claims that the outlaw was at his place when Tex's ranch was attacked. Carolina secretly kills Tombstone, and later, Showdown reminds her of her promise to marry him. Meanwhile, a young Ute woman named Turquoise threatens to reveal that Lucky is The Sidewinder if he refuses to abandon Nora and return to her. Lucky, his hands about her throat, states that a man in his position must marry one of his own kind. Frightened, Turquoise runs away. Tex, who is now the marshal, tells Blaine about Tombstone's alibi, whereupon both men decide to question Jeb. When Jeb is found dead, Tex accompanies Blaine's unit back to town to interrogate their new prime suspect, Lucky. Bursting into Lucky's wedding, Tex and Blaine accuse him of being The Sidewinder. Lucky argues that his wealth makes criminal activities unnecessary, and to prove it, offers to show them his hidden mine. That night, Lucky sends Turquoise to call his band of renegade Utes into action, and the next day, as Tex, the Cavalry and a group of townspeople are riding to Lucky's mine, the Utes attack. During the battle, Carolina and Showdown are killed, and Lucky grabs Nora and escapes to his cliff-dwelling hideout. Tex and Blaine follow Lucky up the ladders to the cliff-dwelling, but as they fight, Turquoise finds a gun and kills Lucky. His arm around Nora, Tex agrees that all bets on the capture of The Sidewinder are off.